將音頻線性PCM轉換爲mp3（使用LAME）低，中，高音頻質量設置

Question

我正在將iOS中的LinearPCM編碼爲MP3。我試圖使用AudioToolbox框架和Lame將PCM的原始PCM數據編碼爲MP3 。雖然一切似乎運行良好，如果我錄製一個音頻它轉換爲MP3播放錄製的MP3音頻文件工作fine.now我現在想轉換音頻（使用跛腳）低，中，高品質的MP3文件。我不知道具體的設置（採樣率，比特深度，比特率，chennal，質量），而蹩腳的轉換過程

void AQRecorder::MyInputBufferHandler( void *        inUserData, 
           AudioQueueRef      inAQ, 
           AudioQueueBufferRef     inBuffer, 
           const AudioTimeStamp *    inStartTime, 
           UInt32        inNumPackets, 
           const AudioStreamPacketDescription* inPacketDesc) 
    { 
    AQRecorder *aqr = (AQRecorder *)inUserData; 
    // NSLog(@"%f",inStartTime->mSampleTime); 
    try 
    { 
    if (inNumPackets > 0) 
    { 
     AudioFileWritePackets(aqr->mRecordFile, FALSE, inBuffer->mAudioDataByteSize, inPacketDesc, aqr->mRecordPacket, &inNumPackets, inBuffer->mAudioData); 

     aqr->mRecordPacket += inNumPackets; 

     int MP3_SIZE =inBuffer->mAudioDataByteSize * 4; 
     unsigned char mp3_buffer[MP3_SIZE]; 
     lame_t lame = lame_init(); 
     lame_set_in_samplerate(lame, 44100); 
     lame_set_VBR(lame, vbr_default); 
     lame_init_params(lame); 

    //    int encodedBytes=lame_encode_buffer_interleaved(lame, (short int *)inBuffer->mAudioData , inNumPackets, mp3_buffer, MP3_SIZE); 


     int encodedBytes = lame_encode_buffer(lame, (short*)inBuffer->mAudioData, (short*)inBuffer->mAudioData, inNumPackets, mp3_buffer, MP3_SIZE); 

     [delegate.mp3AudioData appendBytes:mp3_buffer length:encodedBytes]; 

     if (inBuffer->mAudioDataByteSize != 0) { 
     } 
     else 
     { 
      int encode=lame_encode_flush(lame, mp3_buffer, MP3_SIZE); 
      [delegate.mp3AudioData appendBytes:mp3_buffer length:encode]; 
     } 
     lame_close(lame); 
    } 

    if (aqr->IsRunning()) 
    { 
     AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL); 
    } 
    } catch (CAXException e) 
{ 
char buf[256]; 
fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf)); 
} 
} 

Answer 1

試試這個，

低質量：

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate]; 
     NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init]; 
     [dictAudioQuality setValue:@"Low" forKey:@"audioquality"]; 
     [dictAudioQuality setValue:@"11025" forKey:@"samplerate"]; 
     [dictAudioQuality setValue:@"16" forKey:@"bitdepth"]; 
     [dictAudioQuality setValue:@"120" forKey:@"bitrate"]; 
     [dictAudioQuality setValue:@"1" forKey:@"channel"]; 

中等質量：

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate]; 
     NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init]; 
     [dictAudioQuality setValue:@"Medium" forKey:@"audioquality"]; 
     [dictAudioQuality setValue:@"22050" forKey:@"samplerate"]; 
     [dictAudioQuality setValue:@"16" forKey:@"bitdepth"]; 
     [dictAudioQuality setValue:@"240" forKey:@"bitrate"]; 
     [dictAudioQuality setValue:@"1" forKey:@"channel"]; 

高品質：

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate]; 
     NSMutableDictionary *dictAudioQuality =[[NSMutableDictionary alloc]init]; 
     [dictAudioQuality setValue:@"High" forKey:@"audioquality"]; 
     [dictAudioQuality setValue:@"44100" forKey:@"samplerate"]; 
     [dictAudioQuality setValue:@"24" forKey:@"bitdepth"]; 
     [dictAudioQuality setValue:@"320" forKey:@"bitrate"]; 
     [dictAudioQuality setValue:@"2" forKey:@"channel"]; 

AQRecorder.m開始記錄

void AQRecorder::StartRecord(CFStringRef inRecordFile) 
{ 
int i, bufferByteSize; 
UInt32 size; 

delegate =[[UIApplication sharedApplication]delegate]; 
nSampleRate =[[delegate.dictMP3Quality valueForKey:@"samplerate"] intValue]; 
nBitRate =[[delegate.dictMP3Quality valueForKey:@"bitrate"] intValue]; 
nChannel =[[delegate.dictMP3Quality valueForKey:@"channel"] intValue]; 

try { 

    UInt32 category = kAudioSessionCategory_RecordAudio; 

    OSStatus error = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category), &category); 
    if (error) printf("couldn't set audio category!"); 

    // specify the recording format 
    SetupAudioFormat(kAudioFormatLinearPCM); 

    // create the queue 
    XThrowIfError(AudioQueueNewInput(
            &mRecordFormat, 
            MyInputBufferHandler, 
            this /* userData */, 
            NULL /* run loop */, NULL /* run loop mode */, 
            0 /* flags */, &mQueue), "AudioQueueNewInput failed"); 

    // get the record format back from the queue's audio converter -- 
    // the file may require a more specific stream description than was necessary to create the encoder. 
    mRecordPacket = 0; 

    size = sizeof(mRecordFormat); 
    XThrowIfError(AudioQueueGetProperty(mQueue, kAudioQueueProperty_StreamDescription, 
             &mRecordFormat, &size), "couldn't get queue's format"); 

    // copy the cookie first to give the file object as much info as we can about the data going in 
    // not necessary for pcm, but required for some compressed audio 
    CopyEncoderCookieToFile(); 

    // allocate and enqueue buffers 
    bufferByteSize = ComputeRecordBufferSize(&mRecordFormat, kBufferDurationSeconds); // enough bytes for half a second 
    for (i = 0; i < kNumberRecordBuffers; ++i) { 
     XThrowIfError(AudioQueueAllocateBuffer(mQueue, bufferByteSize, &mBuffers[i]), 
         "AudioQueueAllocateBuffer failed"); 
     XThrowIfError(AudioQueueEnqueueBuffer(mQueue, mBuffers[i], 0, NULL), 
         "AudioQueueEnqueueBuffer failed"); 
    } 
    // start the queue 
    mIsRunning = true; 
    XThrowIfError(AudioQueueStart(mQueue, NULL), "AudioQueueStart failed"); 

    lame = lame_init(); 
    lame_set_in_samplerate(lame, mRecordFormat.mSampleRate); 
    lame_set_out_samplerate(lame, nSampleRate); 
    lame_set_num_channels(lame, nChannel); 
    // lame_set_brate(lame, nBitRate); 
    lame_set_VBR(lame, vbr_default); 
    lame_init_params(lame); 
} 
catch (CAXException e) { 
    char buf[256]; 
    fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf)); 
} 
catch (...) { 
    fprintf(stderr, "An unknown error occurred\n");; 
} 
} 

AQRecorder :: MyInputBufferHandler

void AQRecorder::MyInputBufferHandler( void *        inUserData, 
            AudioQueueRef      inAQ, 
            AudioQueueBufferRef     inBuffer, 
            const AudioTimeStamp *    inStartTime, 
            UInt32        inNumPackets, 
            const AudioStreamPacketDescription* inPacketDesc) 
{ 
AQRecorder *aqr = (AQRecorder *)inUserData; 
try 
{ 

    if (inNumPackets > 0) 
    { 
     AudioFileWritePackets(aqr->mRecordFile, FALSE, inBuffer->mAudioDataByteSize, inPacketDesc, aqr->mRecordPacket, &inNumPackets, inBuffer->mAudioData); 

     aqr->mRecordPacket += inNumPackets; 

     int MP3_SIZE =inNumPackets * 4; 
     unsigned char mp3_buffer[MP3_SIZE]; 

     memset(mp3_buffer, 0, sizeof(mp3_buffer)); 
    // int encodedBytes=lame_encode_buffer_interleaved(lame, (short int*)inBuffer->mAudioData , inNumPackets, mp3_buffer, MP3_SIZE); 

     int encodedBytes = lame_encode_buffer(aqr->lame, (short int*)inBuffer->mAudioData, (short int*)inBuffer->mAudioData, inNumPackets, mp3_buffer, MP3_SIZE); 

     [aqr->delegate.mp3AudioData appendBytes:mp3_buffer length:encodedBytes]; 

     if (inBuffer->mAudioDataByteSize != 0) { 
     } 
     else 
     { 
      int encode=lame_encode_flush(aqr->lame, mp3_buffer, MP3_SIZE); 
      [aqr->delegate.mp3AudioData appendBytes:mp3_buffer length:encode]; 
     } 

     { 
      NSLog(@"------------"); 
      NSLog(@"%d",encodedBytes); 
      NSLog(@"%lu",inNumPackets); 
      NSLog(@"%d",MP3_SIZE); 
      NSLog(@"------------"); 
     } 
    } 

    if (aqr->IsRunning()) 
    { 
     AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL); 
    } 
} catch (CAXException e) 
{ 
    char buf[256]; 
    fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf)); 
} 
}